Dynamic thread status retrieval using inter-thread communication

ABSTRACT

A method for dynamically providing a status of a hardware thread/hardware resource independent of the operation of the hardware thread/hardware resource using an inter-thread communication protocol. A master hardware thread may be configured to communicate status requests to associated slave hardware threads and/or hardware resources. Each slave hardware thread/hardware resource may be configured with hardware logic configured to automatically determine status information for the slave hardware thread/hardware resource and communicate a status response to the master hardware thread without interrupting processing of the slave hardware thread/hardware resource.

DOMESTIC PRIORITY

This application is a continuation application of the legally relatedU.S. Ser. No. 15/018,223 filed Feb. 8, 2016, which is a ContinuationApplication of U.S. application Ser. No. 13/793,458 and issued as U.S.Pat. No. 9,256,574, on Feb. 9, 2016; which is a Continuation Applicationof U.S. application Ser. No. 13/767,133 and issued as U.S. Pat. No.9,256,573, issued on Feb. 9, 2016, the contents of which areincorporated by reference herein in their entirety.

BACKGROUND

The invention is generally related to data processing in a computingsystem including a plurality of interconnected processing blocks, and inparticular to processor architectures and communication architecturesincorporated therein.

A network on a chip (NOC) is a novel integrated circuit architecturethat applies a network-based architecture to a single chip to create aunique processing unit. A typical NOC includes a plurality of integratedprocessor (IP) blocks coupled to one another via the network. NOCprocessing units typically distribute (i.e., allocate) various parts ofa job to different hardware threads of one or more IP blocks to beexecuted by the one or more IP blocks in the NOC processing unit. Withthe number of IP blocks in standard computer systems expected to rise,distributing tasks of a workload to hardware threads of the IP blockshas become increasingly demanding. In general, when distributing aworkload, the status of hardware threads of IP blocks may be useful whendetermining whether to allocate a task to a particular IP block.Retrieving and accumulating thread status information, however, may be aprocessing resource expensive task in systems configured with largenumbers of hardware threads.

A continuing need exists in the art for a manner of increasing theefficiency of workload distribution in computing systems including aplurality of interconnected integrated processor blocks.

SUMMARY

The invention addresses these and other problems associated with theprior art by utilizing a direct inter-thread communication (DITC)interface to communicate status requests from a master hardware threadto one or more slave hardware threads of a computing system. Each slavethread may be associated with status logic that determines the status ofthe slave thread and communicates a status response for the slave threadto the master thread. The master thread may be configured with threadstatus logic that analyzes status responses received from slave threadsand causes the master hardware thread to perform one or more actionsbased on the received status responses. Consistent with embodiments ofthe invention, the status logic of each slave thread may be configuredto automatically respond to a received status request withoutinterrupting processing of the slave thread, i.e., without softwarethread involvement at the slave thread. Hence, embodiments of theinvention dynamically retrieve/collect status related data for one ormore slave threads with a master thread without interrupting theprocessing of software threads at the slave threads using configuredhardware logic and messages communicated over the DITC interface.

Consistent with embodiments of the invention, a status request may bereceived at an inbox of a slave hardware thread from a master hardwarethread. Status logic associated with the slave hardware thread maydetermine a status associated with the first hardware thread in responseto receiving the status request in the inbox. Moreover, consistent withembodiments of the invention, the status logic is configured todetermine the status of the slave hardware thread automatically andcommunicate the determined status independent of softwaredirection/processing at the slave hardware thread, i.e., withoutinterrupting processing of the slave hardware thread. Put another way,the status logic associated with the slave hardware thread determinesthe status of the slave hardware thread independent of the operations ofthe slave hardware thread. Hence, without the slave hardware threadprocessing the status request and/or without a software thread causingthe slave hardware thread to perform an operation to thereby determinethe status of the slave hardware thread, the status of the slavehardware thread is determined and communicated.

These and other advantages and features, which characterize theinvention, are set forth in the claims annexed hereto and forming afurther part hereof. However, for a better understanding of theinvention, and of the advantages and objectives attained through itsuse, reference should be made to the drawings, and to the accompanyingdescriptive matter, in which there is described exemplary embodiments ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of exemplary automated computing machineryincluding an exemplary computer useful in data processing consistentwith embodiments of the present invention.

FIG. 2 is a block diagram of an exemplary NOC implemented in thecomputer of FIG. 1.

FIG. 3 is a block diagram illustrating in greater detail an exemplaryimplementation of a node from the NOC of FIG. 2.

FIG. 4 is a block diagram illustrating an exemplary implementation of anIP block from the NOC of FIG. 2.

FIG. 5 is a block diagram illustrating a master hardware thread, aplurality of interconnected slave hardware threads, and one or moreconnected hardware resources that may be configured in the NOC of FIG.2, and for which status related data may be dynamically collectedconsistent with embodiments of the invention.

FIG. 6 is a flowchart illustrating a sequence of operations that may beperformed by the master hardware thread of FIG. 5 to communicate one ormore status requests to the interconnected slave hardware threads and/orthe one or more hardware resources of FIG. 5.

FIG. 7 is a flowchart illustrating a sequence of operations that may beperformed by the master hardware thread of FIG. 5 to process receivedstatus responses.

FIG. 8 is a flowchart illustrating a sequence of operations that may beperformed by a slave hardware thread and/or hardware resources of FIG. 5responsive to receiving a status request.

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variouspreferred features illustrative of the basic principles of embodimentsof the invention. The specific features consistent with embodiments ofthe invention disclosed herein, including, for example, specificdimensions, orientations, locations, sequences of operations and shapesof various illustrated components, will be determined in part by theparticular intended application, use and/or environment. Certainfeatures of the illustrated embodiments may have been enlarged ordistorted relative to others to facilitate visualization and clearunderstanding.

DETAILED DESCRIPTION

Embodiments of the invention provide a circuit arrangement and methodfor dynamically collecting status data for a plurality of hardwarethreads disposed in a plurality of integrated processing (IP) blockscoupled to one another in a network on a chip (NOC) arrangement.Consistent with embodiments of the invention, a direct inter-threadcommunication (DITC) communication bus is utilized to communicate astatus request from a master hardware thread to an inbox associated withthe slave hardware thread. The slave hardware thread includes statuslogic configured to automatically communicate a status response over theDITC communication bus to the master thread responsive to receiving thestatus request. The status logic of a slave hardware thread isconfigured such that the status of the thread may be determined andcommunicated by the status logic without processing the status requestwith the slave hardware thread.

In embodiments of the invention, a slave hardware thread does notinterrupt processing of a software thread to analyze the status requestmessage, determine the status, and communicate a status response to themaster thread. Instead, the status logic automatically determines thestatus and communicates the status response responsive to receiving thestatus request at the inbox associated with the slave hardware thread.Therefore, embodiments of the invention may realize performanceefficiency benefits because the slave hardware thread is not tasked withprocessing the status response, but instead may continue processingallocated tasks. Moreover, in some embodiments of the invention, statuslogic may be associated with hardware resources that the system may nototherwise be able to determine the status of. Such hardware resourcesmay include, for example, hardware accelerators and/or coprocessors,regular expression engines, compression/decompression engines,encryption/decryption engines, XML parsers, etc. The hardware resourcesmay be configured with status logic, a memory (e.g., a special purposeregister) configured to store status information and an inbox/outboxDITC interface connected to the DITC communication bus such that thestatus of such hardware may be dynamically collected by a master threadconsistent with embodiments of the invention.

In some embodiments, shared inboxes may be associated with subsets ofthe plurality of hardware threads of the NOC system, where the subsetsmay be referred to as “pools” of hardware threads. Inter-threadcommunications may utilize data packets (i.e., “messages”) communicatedto and from the shared inboxes, such that data packets may not beaddressed directly to specific hardware threads but to a pool ofhardware threads associated with a particular shared inbox. The sharedinboxes may receive work requests from any of the hardware threads ofthe pool associated therewith and communicate data packets to therequesting hardware threads. In some embodiments, a respective sharedinbox may be associated with a pool of hardware threads executing thesame and/or related software threads, including for example, a pool ofhardware threads executing instances of a stage of a software pipeline.As such, a shared inbox may manage workload balancing between hardwarethreads of an associated pool of hardware threads by communicating datapackets to such hardware threads for processing upon request of suchhardware threads.

Hardware and Software Environment

Now turning to the drawings, wherein like numbers denote like partsthroughout the several views, FIG. 1 illustrates exemplary automatedcomputing machinery including an exemplary computer 10 useful in dataprocessing consistent with embodiments of the present invention.Computer 10 of FIG. 1 includes at least one computer processor 12 or‘CPU’ as well as random access memory 14 (‘RAM’), which is connectedthrough a high speed memory bus 16 and bus adapter 18 to processor 12and to other components of the computer 10.

Stored in RAM 14 is an application program 20, a module of user-levelcomputer program instructions for carrying out particular dataprocessing tasks such as, for example, word processing, spreadsheets,database operations, video gaming, stock market simulations, atomicquantum process simulations, or other user-level applications. Alsostored in RAM 14 is an operating system 22. Operating systems useful inconnection with embodiments of the invention include UNIX™, Linux™,Microsoft Windows XP™, AIX™, IBM's i5/OS™, and others as will occur tothose of skill in the art. Operating system 22 and application 20 in theexample of FIG. 1 are shown in RAM 14, but many components of suchsoftware typically are stored in non-volatile memory also, e.g., on adisk drive 24.

As will become more apparent below, embodiments consistent with theinvention may be implemented within Network On Chip (NOC) integratedcircuit devices, or chips, and as such, computer 10 is illustratedincluding two exemplary NOCs: a video adapter 26 and a coprocessor 28.NOC video adapter 26, which may alternatively be referred to as agraphics adapter, is an example of an I/O adapter specially designed forgraphic output to a display device 30 such as a display screen orcomputer monitor. NOC video adapter 26 is connected to processor 12through a high speed video bus 32, bus adapter 18, and the front sidebus 34, which is also a high speed bus. NOC Coprocessor 28 is connectedto processor 12 through bus adapter 18, and front side buses 34 and 36,which is also a high speed bus. The NOC coprocessor of FIG. 1 may beoptimized, for example, to accelerate particular data processing tasksat the behest of the main processor 12.

The exemplary NOC video adapter 26 and NOC coprocessor 28 of FIG. 1 eachinclude a NOC, including integrated processor (‘IP’) blocks, routers,memory communications controllers, and network interface controllers,the details of which will be discussed in greater detail below inconnection with FIGS. 2-3. The NOC video adapter and NOC coprocessor areeach optimized for programs that use parallel processing and alsorequire fast random access to shared memory. It will be appreciated byone of ordinary skill in the art having the benefit of the instantdisclosure, however, that the invention may be implemented in devicesand device architectures other than NOC devices and devicearchitectures. The invention is therefore not limited to implementationwithin an NOC device.

Computer 10 of FIG. 1 includes disk drive adapter 38 coupled through anexpansion bus 40 and bus adapter 18 to processor 12 and other componentsof the computer 10. Disk drive adapter 38 connects non-volatile datastorage to the computer 10 in the form of disk drive 24, and may beimplemented, for example, using Integrated Drive Electronics (‘IDE’)adapters, Small Computer System Interface (‘SCSI’) adapters, and othersas will occur to those of skill in the art. Non-volatile computer memoryalso may be implemented for as an optical disk drive, electricallyerasable programmable read-only memory (so-called ‘EEPROM’ or ‘Flash’memory), RAM drives, and so on, as will occur to those of skill in theart.

Computer 10 also includes one or more input/output (‘I/O’) adapters 42,which implement user-oriented input/output through, for example,software drivers and computer hardware for controlling output to displaydevices such as computer display screens, as well as user input fromuser input devices 44 such as keyboards and mice. In addition, computer10 includes a communications adapter 46 for data communications withother computers 48 and for data communications with a datacommunications network 50. Such data communications may be carried outserially through RS-232 connections, through external buses such as aUniversal Serial Bus (‘USB’), through data communications datacommunications networks such as IP data communications networks, and inother ways as will occur to those of skill in the art. Communicationsadapters implement the hardware level of data communications throughwhich one computer sends data communications to another computer,directly or through a data communications network. Examples ofcommunications adapters suitable for use in computer 10 include modemsfor wired dial-up communications, Ethernet (IEEE 802.3) adapters forwired data communications network communications, and 802.11 adaptersfor wireless data communications network communications.

For further explanation, FIG. 2 sets forth a functional block diagram ofan example NOC 102 according to embodiments of the present invention.The NOC in FIG. 2 is implemented on a ‘chip’ 100, that is, on anintegrated circuit. NOC 102 includes integrated processor (‘IP’) blocks104, routers 110, memory communications controllers 106, and networkinterface controllers 108 grouped into interconnected nodes. Each IPblock 104 is adapted to a router 110 through a memory communicationscontroller 106 and a network interface controller 108. Each memorycommunications controller controls communications between an IP blockand memory, and each network interface controller 108 controls inter-IPblock communications through routers 110.

In NOC 102, each IP block represents a reusable unit of synchronous orasynchronous logic design used as a building block for data processingwithin the NOC. The term ‘IP block’ is sometimes expanded as‘intellectual property block,’ effectively designating an IP block as adesign that is owned by a party, that is the intellectual property of aparty, to be licensed to other users or designers of semiconductorcircuits. In the scope of the present invention, however, there is norequirement that IP blocks be subject to any particular ownership, sothe term is always expanded in this specification as ‘integratedprocessor block.’ IP blocks, as specified here, are reusable units oflogic, cell, or chip layout design that may or may not be the subject ofintellectual property. IP blocks are logic cores that can be formed asASIC chip designs or FPGA logic designs.

One way to describe IP blocks by analogy is that IP blocks are for NOCdesign what a library is for computer programming or a discreteintegrated circuit component is for printed circuit board design. InNOCs consistent with embodiments of the present invention, IP blocks maybe implemented as generic gate netlists, as complete special purpose orgeneral purpose microprocessors, or in other ways as may occur to thoseof skill in the art. A netlist is a Boolean-algebra representation(gates, standard cells) of an IP block's logical-function, analogous toan assembly-code listing for a high-level program application. NOCs alsomay be implemented, for example, in synthesizable form, described in ahardware description language such as Verilog or VHDL. In addition tonetlist and synthesizable implementation, NOCs also may be delivered inlower-level, physical descriptions. Analog IP block elements such asSERDES, PLL, DAC, ADC, and so on, may be distributed in atransistor-layout format such as GDSII. Digital elements of IP blocksare sometimes offered in layout format as well. It will also beappreciated that IP blocks, as well as other logic circuitry implementedconsistent with the invention may be distributed in the form of computerdata files, e.g., logic definition program code, that define at variouslevels of detail the functionality and/or layout of the circuitarrangements implementing such logic. Thus, while the invention has andhereinafter will be described in the context of circuit arrangementsimplemented in fully functioning integrated circuit devices, dataprocessing systems utilizing such devices, and other tangible, physicalhardware circuits, those of ordinary skill in the art having the benefitof the instant disclosure will appreciate that the invention may also beimplemented within a program product, and that the invention appliesequally regardless of the particular type of computer readable storagemedium being used to distribute the program product. Examples ofcomputer readable storage media include, but are not limited to,physical, recordable type media such as volatile and non-volatile memorydevices, floppy disks, hard disk drives, CD-ROMs, and DVDs (amongothers).

Each IP block 104 in the example of FIG. 2 is adapted to a router 110through a memory communications controller 106. Each memorycommunication controller is an aggregation of synchronous andasynchronous logic circuitry adapted to provide data communicationsbetween an IP block and memory. Examples of such communications betweenIP blocks and memory include memory load instructions and memory storeinstructions. The memory communications controllers 106 are described inmore detail below with reference to FIG. 3. Each IP block 104 is alsoadapted to a router 110 through a network interface controller 108,which controls communications through routers 110 between IP blocks 104.Examples of communications between IP blocks include messages carryingdata and instructions for processing the data among IP blocks inparallel applications and in pipelined applications. The networkinterface controllers 108 are also described in more detail below withreference to FIG. 3.

Routers 110, and the corresponding links 118 therebetween, implement thenetwork operations of the NOC. The links 118 may be packet structuresimplemented on physical, parallel wire buses connecting all the routers.That is, each link may be implemented on a wire bus wide enough toaccommodate simultaneously an entire data switching packet, includingall header information and payload data. If a packet structure includes64 bytes, for example, including an eight byte header and 56 bytes ofpayload data, then the wire bus subtending each link is 64 bytes wide,512 wires. In addition, each link may be bi-directional, so that if thelink packet structure includes 64 bytes, the wire bus actually contains1024 wires between each router and each of its neighbors in the network.In such an implementation, a message could include more than one packet,but each packet would fit precisely onto the width of the wire bus. Inthe alternative, a link may be implemented on a wire bus that is onlywide enough to accommodate a portion of a packet, such that a packetwould be broken up into multiple beats, e.g., so that if a link isimplemented as 16 bytes in width, or 128 wires, a 64 byte packet couldbe broken into four beats. It will be appreciated that differentimplementations may used different bus widths based on practicalphysical limits as well as desired performance characteristics. If theconnection between the router and each section of wire bus is referredto as a port, then each router includes five ports, one for each of fourdirections of data transmission on the network and a fifth port foradapting the router to a particular IP block through a memorycommunications controller and a network interface controller.

Each memory communications controller 106 controls communicationsbetween an IP block and memory. Memory can include off-chip main RAM112, memory 114 connected directly to an IP block through a memorycommunications controller 106, on-chip memory enabled as an IP block116, and on-chip caches. In NOC 102, either of the on-chip memories 114,116, for example, may be implemented as on-chip cache memory. All theseforms of memory can be disposed in the same address space, physicaladdresses or virtual addresses, true even for the memory attacheddirectly to an IP block. Memory addressed messages therefore can beentirely bidirectional with respect to IP blocks, because such memorycan be addressed directly from any IP block anywhere on the network.Memory 116 on an IP block can be addressed from that IP block or fromany other IP block in the NOC. Memory 114 attached directly to a memorycommunication controller can be addressed by the IP block that isadapted to the network by that memory communication controller—and canalso be addressed from any other IP block anywhere in the NOC.

NOC 102 includes two memory management units (‘MMUs’) 120, 122,illustrating two alternative memory architectures for NOCs consistentwith embodiments of the present invention. MMU 120 is implemented withinan IP block, allowing a processor within the IP block to operate invirtual memory while allowing the entire remaining architecture of theNOC to operate in a physical memory address space. MMU 122 isimplemented off-chip, connected to the NOC through a data communicationsport 124. The port 124 includes the pins and other interconnectionsrequired to conduct signals between the NOC and the MMU, as well assufficient intelligence to convert message packets from the NOC packetformat to the bus format required by the external MMU 122. The externallocation of the MMU means that all processors in all IP blocks of theNOC can operate in virtual memory address space, with all conversions tophysical addresses of the off-chip memory handled by the off-chip MMU122.

In addition to the two memory architectures illustrated by use of theMMUs 120, 122, data communications port 126 illustrates a third memoryarchitecture useful in NOCs capable of being utilized in embodiments ofthe present invention. Port 126 provides a direct connection between anIP block 104 of the NOC 102 and off-chip memory 112. With no MMU in theprocessing path, this architecture provides utilization of a physicaladdress space by all the IP blocks of the NOC. In sharing the addressspace bi-directionally, all the IP blocks of the NOC can access memoryin the address space by memory-addressed messages, including loads andstores, directed through the IP block connected directly to the port126. The port 126 includes the pins and other interconnections requiredto conduct signals between the NOC and the off-chip memory 112, as wellas sufficient intelligence to convert message packets from the NOCpacket format to the bus format required by the off-chip memory 112.

In the example of FIG. 2, one of the IP blocks is designated a hostinterface processor 128. A host interface processor 128 provides aninterface between the NOC and a host computer 10 in which the NOC may beinstalled and also provides data processing services to the other IPblocks on the NOC, including, for example, receiving and dispatchingamong the IP blocks of the NOC data processing requests from the hostcomputer. A NOC may, for example, implement a video graphics adapter 26or a coprocessor 28 on a larger computer 10 as described above withreference to FIG. 1. In the example of FIG. 2, the host interfaceprocessor 128 is connected to the larger host computer through a datacommunications port 130. The port 130 includes the pins and otherinterconnections required to conduct signals between the NOC and thehost computer, as well as sufficient intelligence to convert messagepackets from the NOC to the bus format required by the host computer 10.In the example of the NOC coprocessor in the computer of FIG. 1, such aport would provide data communications format translation between thelink structure of the NOC coprocessor 28 and the protocol required forthe front side bus 36 between the NOC coprocessor 28 and the bus adapter18.

FIG. 3 next illustrates a functional block diagram illustrating ingreater detail the components implemented within an IP block 104, memorycommunications controller 106, network interface controller 108 androuter 110 in NOC 102, collectively illustrated at 132 which may bereferred to as a node or a hardware thread. IP block 104 includes acomputer processor 134 and I/O functionality 136. In this example,computer memory is represented by a segment of random access memory(‘RAM’) 138 in IP block 104. The memory, as described above withreference to FIG. 2, can occupy segments of a physical address spacewhose contents on each IP block are addressable and accessible from anyIP block in the NOC. The processors 134, I/O capabilities 136, andmemory 138 in each IP block effectively implement the IP blocks asgenerally programmable microcomputers. As explained above, however, inthe scope of the present invention, IP blocks generally representreusable units of synchronous or asynchronous logic used as buildingblocks for data processing within a NOC. Implementing IP blocks asgenerally programmable microcomputers, therefore, although a commonembodiment useful for purposes of explanation, is not a limitation ofthe present invention.

In NOC 102 of FIG. 3, each memory communications controller 106 includesa plurality of memory communications execution engines 140. Each memorycommunications execution engine 140 is enabled to execute memorycommunications instructions from an IP block 104, includingbidirectional memory communications instruction flow 141, 142, 144between the network and the IP block 104. The memory communicationsinstructions executed by the memory communications controller mayoriginate, not only from the IP block adapted to a router through aparticular memory communications controller, but also from any IP block104 anywhere in NOC 102. That is, any IP block in the NOC can generate amemory communications instruction and transmit that memorycommunications instruction through the routers of the NOC to anothermemory communications controller associated with another IP block forexecution of that memory communications instruction. Such memorycommunications instructions can include, for example, translationlookaside buffer control instructions, cache control instructions,barrier instructions, and memory load and store instructions.

Each memory communications execution engine 140 is enabled to execute acomplete memory communications instruction separately and in parallelwith other memory communications execution engines. The memorycommunications execution engines implement a scalable memory transactionprocessor optimized for concurrent throughput of memory communicationsinstructions. Memory communications controller 106 supports multiplememory communications execution engines 140 all of which runconcurrently for simultaneous execution of multiple memorycommunications instructions. A new memory communications instruction isallocated by the memory communications controller 106 to a memorycommunications engine 140 and memory communications execution engines140 can accept multiple response events simultaneously. In this example,all of the memory communications execution engines 140 are identical.Scaling the number of memory communications instructions that can behandled simultaneously by a memory communications controller 106,therefore, is implemented by scaling the number of memory communicationsexecution engines 140.

In NOC 102 of FIG. 3, each network interface controller 108 is enabledto convert communications instructions from command format to networkpacket format for transmission among the IP blocks 104 through routers110. The communications instructions may be formulated in command formatby the IP block 104 or by memory communications controller 106 andprovided to the network interface controller 108 in command format. Thecommand format may be a native format that conforms to architecturalregister files of IP block 104 and memory communications controller 106.The network packet format is typically the format required fortransmission through routers 110 of the network. Each such message iscomposed of one or more network packets. Examples of such communicationsinstructions that are converted from command format to packet format inthe network interface controller include memory load instructions andmemory store instructions between IP blocks and memory. Suchcommunications instructions may also include communications instructionsthat send messages among IP blocks carrying data and instructions forprocessing the data among IP blocks in parallel applications and inpipelined applications.

In NOC 102 of FIG. 3, each IP block is enabled to sendmemory-address-based communications to and from memory through the IPblock's memory communications controller and then also through itsnetwork interface controller to the network. A memory-address-basedcommunications is a memory access instruction, such as a loadinstruction or a store instruction, that is executed by a memorycommunication execution engine of a memory communications controller ofan IP block. Such memory-address-based communications typicallyoriginate in an IP block, formulated in command format, and handed offto a memory communications controller for execution.

Many memory-address-based communications are executed with messagetraffic, because any memory to be accessed may be located anywhere inthe physical memory address space, on-chip or off-chip, directlyattached to any memory communications controller in the NOC, orultimately accessed through any IP block of the NOC—regardless of whichIP block originated any particular memory-address-based communication.Thus, in NOC 102, all memory-address-based communications that areexecuted with message traffic are passed from the memory communicationscontroller to an associated network interface controller for conversionfrom command format to packet format and transmission through thenetwork in a message. In converting to packet format, the networkinterface controller also identifies a network address for the packet independence upon the memory address or addresses to be accessed by amemory-address-based communication. Memory address based messages areaddressed with memory addresses. Each memory address is mapped by thenetwork interface controllers to a network address, typically thenetwork location of a memory communications controller responsible forsome range of physical memory addresses. The network location of amemory communication controller 106 is naturally also the networklocation of that memory communication controller's associated router110, network interface controller 108, and IP block 104. The instructionconversion logic 150 within each network interface controller is capableof converting memory addresses to network addresses for purposes oftransmitting memory-address-based communications through routers of aNOC.

Upon receiving message traffic from routers 110 of the network, eachnetwork interface controller 108 inspects each packet for memoryinstructions. Each packet containing a memory instruction is handed tothe memory communications controller 106 associated with the receivingnetwork interface controller, which executes the memory instructionbefore sending the remaining payload of the packet to the IP block forfurther processing. In this way, memory contents are always prepared tosupport data processing by an IP block before the IP block beginsexecution of instructions from a message that depend upon particularmemory content.

In NOC 102 of FIG. 3, each IP block 104 is enabled to bypass its memorycommunications controller 106 and send inter-IP block, network-addressedcommunications 146 directly to the network through the IP block'snetwork interface controller 108. Network-addressed communications aremessages directed by a network address to another IP block. Suchmessages transmit working data in pipelined applications, multiple datafor single program processing among IP blocks in a SIMD application, andso on, as will occur to those of skill in the art. Such messages aredistinct from memory-address-based communications in that they arenetwork addressed from the start, by the originating IP block whichknows the network address to which the message is to be directed throughrouters of the NOC. Such network-addressed communications are passed bythe IP block through I/O functions 136 directly to the IP block'snetwork interface controller in command format, then converted to packetformat by the network interface controller and transmitted throughrouters of the NOC to another IP block. Such network-addressedcommunications 146 are bi-directional, potentially proceeding to andfrom each IP block of the NOC, depending on their use in any particularapplication. Each network interface controller, however, is enabled toboth send and receive such communications to and from an associatedrouter, and each network interface controller is enabled to both sendand receive such communications directly to and from an associated IPblock, bypassing an associated memory communications controller 106.

Each network interface controller 108 in the example of FIG. 3 is alsoenabled to implement virtual channels on the network, characterizingnetwork packets by type. Each network interface controller 108 includesvirtual channel implementation logic 148 that classifies eachcommunication instruction by type and records the type of instruction ina field of the network packet format before handing off the instructionin packet form to a router 110 for transmission on the NOC. Examples ofcommunication instruction types include inter-IP blocknetwork-address-based messages, request messages, responses to requestmessages, invalidate messages directed to caches; memory load and storemessages; and responses to memory load messages, etc.

Each router 110 in the example of FIG. 3 includes routing logic 152,virtual channel control logic 154, and virtual channel buffers 156. Therouting logic typically is implemented as a network of synchronous andasynchronous logic that implements a data communications protocol stackfor data communication in the network formed by the routers 110, links118, and bus wires among the routers. Routing logic 152 includes thefunctionality that readers of skill in the art might associate inoff-chip networks with routing tables, routing tables in at least someembodiments being considered too slow and cumbersome for use in a NOC.Routing logic implemented as a network of synchronous and asynchronouslogic can be configured to make routing decisions as fast as a singleclock cycle. The routing logic in this example routes packets byselecting a port for forwarding each packet received in a router. Eachpacket contains a network address to which the packet is to be routed.

In describing memory-address-based communications above, each memoryaddress was described as mapped by network interface controllers to anetwork address, a network location of a memory communicationscontroller. The network location of a memory communication controller106 is naturally also the network location of that memory communicationcontroller's associated router 110, network interface controller 108,and IP block 104. In inter-IP block, or network-address-basedcommunications, therefore, it is also typical for application-level dataprocessing to view network addresses as the location of an IP blockwithin the network formed by the routers, links, and bus wires of theNOC. FIG. 2 illustrates that one organization of such a network is amesh of rows and columns in which each network address can beimplemented, for example, as either a unique identifier for each set ofassociated router, IP block, memory communications controller, andnetwork interface controller of the mesh or x, y coordinates of eachsuch set in the mesh.

In NOC 102 of FIG. 3, each router 110 implements two or more virtualcommunications channels, where each virtual communications channel ischaracterized by a communication type. Communication instruction types,and therefore virtual channel types, include those mentioned above:inter-IP block network-address-based messages, request messages,responses to request messages, invalidate messages directed to caches;memory load and store messages; and responses to memory load messages,and so on. In support of virtual channels, each router 110 in theexample of FIG. 3 also includes virtual channel control logic 154 andvirtual channel buffers 156. The virtual channel control logic 154examines each received packet for its assigned communications type andplaces each packet in an outgoing virtual channel buffer for thatcommunications type for transmission through a port to a neighboringrouter on the NOC.

Each virtual channel buffer 156 has finite storage space. When manypackets are received in a short period of time, a virtual channel buffercan fill up—so that no more packets can be put in the buffer. In otherprotocols, packets arriving on a virtual channel whose buffer is fullwould be dropped. Each virtual channel buffer 156 in this example,however, is enabled with control signals of the bus wires to advisesurrounding routers through the virtual channel control logic to suspendtransmission in a virtual channel, that is, suspend transmission ofpackets of a particular communications type. When one virtual channel isso suspended, all other virtual channels are unaffected—and can continueto operate at full capacity. The control signals are wired all the wayback through each router to each router's associated network interfacecontroller 108. Each network interface controller is configured to, uponreceipt of such a signal, refuse to accept, from its associated memorycommunications controller 106 or from its associated IP block 104,communications instructions for the suspended virtual channel. In thisway, suspension of a virtual channel affects all the hardware thatimplements the virtual channel, all the way back up to the originatingIP blocks.

One effect of suspending packet transmissions in a virtual channel isthat no packets are ever dropped. When a router encounters a situationin which a packet might be dropped in some unreliable protocol such as,for example, the Internet Protocol, the routers in the example of FIG. 3may suspend by their virtual channel buffers 156 and their virtualchannel control logic 154 all transmissions of packets in a virtualchannel until buffer space is again available, eliminating any need todrop packets. The NOC of FIG. 3, therefore, may implement highlyreliable network communications protocols with an extremely thin layerof hardware.

The example NOC of FIG. 3 may also be configured to maintain cachecoherency between both on-chip and off-chip memory caches. Each NOC cansupport multiple caches each of which operates against the sameunderlying memory address space. For example, caches may be controlledby IP blocks, by memory communications controllers, or by cachecontrollers external to the NOC. Either of the on-chip memories 114, 116in the example of FIG. 2 may also be implemented as an on-chip cache,and, within the scope of the present invention, cache memory can beimplemented off-chip also.

Each router 110 illustrated in FIG. 3 includes five ports, four ports158A-D connected through bus wires 118 to other routers and a fifth port160 connecting each router to its associated IP block 104 through anetwork interface controller 108 and a memory communications controller106. As can be seen from the illustrations in FIGS. 2 and 3, the routers110 and the links 118 of the NOC 102 form a mesh network with verticaland horizontal links connecting vertical and horizontal ports in eachrouter. In the illustration of FIG. 3, for example, ports 158A, 158C and160 are termed vertical ports, and ports 158B and 158D are termedhorizontal ports.

FIG. 4 next illustrates in another manner one exemplary implementationof an IP block 104 consistent with the invention, implemented as aprocessing element partitioned into an instruction unit (IU) 162,execution unit (XU) 164 and auxiliary execution unit (AXU) 166. In theillustrated implementation, IU 162 includes a plurality of instructionbuffers 168 that receive instructions from an L1 instruction cache(iCACHE) 170. Each instruction buffer 168 is dedicated to one of aplurality, e.g., four, symmetric multithreaded (SMT) hardware threads.An effective-to-real translation unit (iERAT) 172 is coupled to iCACHE170, and is used to translate instruction fetch requests from aplurality of thread fetch sequencers 174 into real addresses forretrieval of instructions from lower order memory. Each thread fetchsequencer 174 is dedicated to a particular hardware thread, and is usedto ensure that instructions to be executed by the associated thread isfetched into the iCACHE for dispatch to the appropriate execution unit.As also shown in FIG. 4, instructions fetched into instruction buffer168 may also be monitored by branch prediction logic 176, which provideshints to each thread fetch sequencer 174 to minimize instruction cachemisses resulting from branches in executing threads.

IU 162 also includes a dependency/issue logic block 178 dedicated toeach hardware thread, and configured to resolve dependencies and controlthe issue of instructions from instruction buffer 168 to XU 164. Inaddition, in the illustrated embodiment, separate dependency/issue logic180 is provided in AXU 166, thus enabling separate instructions to beconcurrently issued by different threads to XU 164 and AXU 166. In analternative embodiment, logic 180 may be disposed in IU 162, or may beomitted in its entirety, such that logic 178 issues instructions to AXU166.

XU 164 is implemented as a fixed point execution unit, including a setof general purpose registers (GPR's) 182 coupled to fixed point logic184, branch logic 186 and load/store logic 188. Load/store logic 188 iscoupled to an L1 data cache (dCACHE) 190, with effective to realtranslation provided by dERAT logic 192. XU 164 may be configured toimplement practically any instruction set, e.g., all or a portion of a32b or 64b PowerPC instruction set.

AXU 166 operates as an auxiliary execution unit including dedicateddependency/issue logic 180 along with one or more execution blocks 194.AXU 166 may include any number of execution blocks, and may implementpractically any type of execution unit, e.g., a floating point unit, orone or more specialized execution units such as encryption/decryptionunits, coprocessors, vector processing units, graphics processing units,XML processing units, etc. In the illustrated embodiment, AXU 166includes a high speed auxiliary interface to XU 164, e.g., to supportdirect moves between AXU architected state and XU architected state.

Communication with IP block 104 may be managed in the manner discussedabove in connection with FIG. 2, via network interface controller 108coupled to NOC 102. Address-based communication, e.g., to access L2cache memory, may be provided, along with message-based communication.For example, each IP block 104 may include a dedicated in box and/or outbox in order to handle inter-node communications between IP blocks.

Embodiments of the present invention may be implemented within thehardware and software environment described above in connection withFIGS. 1-4. However, it will be appreciated by one of ordinary skill inthe art having the benefit of the instant disclosure that the inventionmay be implemented in a multitude of different environments, and thatother modifications may be made to the aforementioned hardware andsoftware embodiment without departing from the spirit and scope of theinvention. As such, the invention is not limited to the particularhardware and software environment disclosed herein.

Dynamic Thread Status Retrieval Using Inter-Thread Communication

NOC systems utilizing direct inter-thread communication (DITC) include aplurality of interconnected IP blocks configured within a plurality ofhardware threads. In embodiments of the invention, an inbox/outbox modelis used, whereby transmitting data packets is may be referred to as“message passing,” and a message (i.e., a data packet) is transmittedfrom an output buffer (i.e., an “outbox”) of a first hardware thread toan input buffer (i.e., an “inbox”) of a second hardware thread over thenetwork of the NOC. As such, each hardware thread of a DITCimplementation includes an inbox and an outbox, and messages passed overthe network of the NOC include an address corresponding to therespective destination hardware thread (or pool of hardware threads) towhich the message is to be passed.

Embodiments of the invention perform status retrieval/collection for oneor more hardware threads by communicating status requests and responsesas DITC messages. Particularly, a particular hardware thread may processa software thread that causes the particular hardware thread to performas a master hardware thread for one or more slave hardware threadsand/or hardware resources connected to the network of the NOC.Consistent with embodiments of the invention, the master hardware threadmay communicate a status request to one or more slave hardware threads,receive responses from the slave hardware threads and perform one ormore operations in response. For example, the master hardware thread maystore status information for one or more slave hardware threads to amemory location, such as an external memory location and/or a localbuffer. As further examples, the master hardware thread may communicatea status notification to executing software; the master hardware threadmay communicate a message responsive to a status response thatinterrupts software execution; the master hardware thread may filterand/or ignore status responses of particular type(s) while performingoperation(s) responsive to receiving other type(s) of responses.

Each slave hardware thread may be configured with status logicconfigured to automatically determine a status of the slave hardwarethread and communicate a status response DITC message over the networkof the NOC responsive to receiving a status request from the masterthread at the inbox of the slave hardware thread. Consistent withembodiments of the invention, the status logic is configured to performsuch operations independent of the operation of the slave hardwarethread. Therefore, the status of the slave hardware thread may bedetermined and communicated without interrupting processing of the slavehardware thread, which may provide performance and efficiency benefitsas compared to interrupting processing at the slave hardware thread toprocess the status request at the slave hardware thread. Moreover, thestatus of the slave hardware thread may be determined and communicatedwithout initializing operation of the slave hardware thread if the slavehardware thread is in a low-power idle operation mode and/or powereddown, which may provide efficiency benefits as compared towaking/powering up the slave hardware thread to process the statusrequest at the slave hardware thread.

Turning now to FIG. 5, this figure provides a block diagram illustratinga master hardware thread 200 (also referred to herein as master thread),connected slave hardware threads 202 a,b (also referred to herein asslave threads), and one or more connected hardware resources 204 incommunication over a communication bus 206 that status information maybe dynamically retrieved/collected from by the master thread 200.Consistent with DITC messaging, the master thread 200, slave threads 202a,b, and the one or more hardware resources 204 each include a DITCinbox 208 and outbox 210. Each inbox 208 is configured to receive DITCmessages directed to the associated hardware thread 200, 202 a,b, and/orhardware resources 204 from the communication bus 206, and each outboxis configured to send DITC messages over the communication bus 206.

The master thread 200 includes thread status logic 212 that isconfigured to communicate a status request to one or more of the slavethreads 202 a,b and/or one or more hardware resources 204. In someembodiments, the thread status logic 212 may selectively communicatestatus requests to particular slave threads 202 a, b and/or hardwareresources 204, or the thread status logic 212 may communicate statusrequests to all associated slave threads 202 a,b and/or hardwareresources 204. The thread status logic 212 is further configured toprocess status responses received at the inbox 208 of the master thread200. In general, the thread status logic 212 may be configured to storestatus information in a memory based on received status responses,communicate a notification based on received status responses, interruptsoftware execution based on received status responses, collect andfilter status responses to perform the operations responsive toparticular types of status responses, and/or other such operations.

Each slave thread 202 a,b and any hardware resources 204 associated withthe master thread 200 may be configured with status logic 214 and astatus register 216. The status logic 214 may monitor the inbox 208 todetect receipt of a status request from the master thread 200. Inresponse to receiving a status response, the status logic 214 maydetermine a status associated with the corresponding slave thread 202a,b or hardware resource 204 and the status logic 214 may communicate astatus response as a DITC message based on the determined status. Thestatus logic 214 may determine the status of the corresponding slavethread 202 a,b and/or hardware resource 204 by accessing the statusregister 216, where the status register may store status information forthe corresponding slave thread 202 a,b and/or hardware resource 204. Thestatus register 216 may be a special purpose register configured tostore status information and/or any type of memory designated to storestatus information. The status register 216 may store counterinformation and/or other such relevant information corresponding to thecorresponding slave thread 202 a,b or hardware resource 204 thatindicates performance of the corresponding slave thread 202 a,b orhardware resource 204.

Turning now to FIG. 6, this figure provides a flowchart 250 thatillustrates a sequence of operations that may be performed by a masterhardware thread consistent with embodiments of the invention todynamically retrieve/collect status information for one or moreassociated slave hardware threads and/or hardware resources. Asdiscussed, the master thread may retrieve status information forassociated slave hardware threads as well as configured hardwareresources, hence, where the remaining examples and description refer toslave hardware threads, it should be understood that hardware resourcesconsistent with embodiments of the invention may be consideredinterchangeable with the slave hardware threads. The master hardwarethread may communicate a configuration message to all hardware threadsdesired to be managed by the master thread (block 252). In general, theconfiguration message configures all the slave threads for statusretrieval by the master thread. For example, based on the configurationmessage, a status register may be configured to store status informationin a particular format (e.g., store a performance counter), and statuslogic may be configured to communicate a status response includingspecified status information in a particular format.

The master thread may determine slave threads from which statusinformation is to be retrieved/collected (block 254). In general, themaster thread may communicate status request to one or more targetedslave threads or a status request may be communicated to all associatedslave threads. The master thread is configured to process a softwarethread that causes the master thread to perform operations associatedwith the master thread as described herein. Hence, the master thread maytarget particular slave threads for status retrieval and/or retrieve astatus from all associated hardware threads based on the software threadthat is processed by the master thread. The master thread communicates astatus request as a DITC message to the one or more determined slavethreads (block 256). The master thread may be configured monitor statusresponse time from slave threads (block 258), and if a status responseis not received within a defined amount of time (“Y” branch of block258), the master thread may communicate a notification (block 260). Ingeneral, the master thread may communicate a notification such that anexecuting software and/or operating system generating a workload for thehardware threads may be notified that a slave thread is non-responsive.The master thread may receive status responses as DITC messages for thecommunicated status requests (block 262).

FIG. 7 provides a flowchart 280 that illustrates a sequence ofoperations that may be performed by a master thread in response toreceiving a status response from a slave thread (block 282). In someembodiments of the invention, the master thread may be configured toaccumulate status responses (i.e., store, collect, and/or aggregate)(block 284). In addition, if the master thread is configured toaccumulate status responses (“Y” branch of block 284), the master threadmay be configured to filter the status responses such that onlyparticular types of responses are stored (block 286). If the masterthread is configured to filter received status responses (“Y” branch ofblock 286), the master thread may filter the received status responses(block 288) using masks and comparison logic configured in thread statuslogic to determine whether a received status response is of a type thatmay be stored to memory (block 290). If the master thread is notconfigured to filter status responses (“N” branch of block 286), themaster thread may store received status responses to memory (block 290).For example, the master thread may be configured to filter statusresponses that indicate that a slave thread is operating normally, andthe master thread may be configured to store status responses thatindicate that a slave thread is not operating normally.

Returning to block 284, if the master thread is not configured toaccumulate status responses (“N” branch of block 284), the master threadmay be configured to interrupt software execution based on whether areceived status response is of a particular type (block 292). If themaster thread is configured to interrupt software execution based on astatus response and a received status response is of a type for whichthe master thread is configured to interrupt software execution for (“Y”branch of block 292), the master thread may communicate an interruptmessage (e.g., command/notification) (block 294). Sending the interruptmessage may comprise communicating a DITC message to one or moreconnected hardware threads (which may be more threads that thoseconfigured as slave threads), and/or sending the interrupt message maycomprise communicating data to a memory location that may be monitoredfor interrupt commands/notifications.

If the master thread is not configured to interrupt software executionbased on receiving a status response of a particular type and/or if themaster thread does not receive a status response of the particular type(“N” branch of block 292), the master thread may be configured to ignoreparticular types of status responses (block 296). If the master threadis configured to ignore particular types of status responses and themaster thread receives a status response of the particular type (“Y”branch of block 296), the master thread may discard the status response(block 298). If the status response is not of the particular type (“N”branch of block 296), the master thread may store the status response tomemory (block 290). Hence, the master thread may be configured to ignoreparticular types of status responses and store only particular types.For example, if a first status response indicates that a particularslave thread is processing and assigned tasks of the workload, and asecond status response received at a later time indicates the samestatus for the particular slave thread, the master thread may discardthe second status response as the status has not changed. However, ifthe second status response indicates that the particular hardware threadhas completed processing tasks, the master thread may store the statusof the status message to memory, as the second status response indicatedthat the status changed for the particular hardware thread.

FIG. 8 provides a flowchart 320 that illustrates a sequence ofoperations that may be performed by a slave thread and/or hardwareresource consistent with embodiments of the invention in response toreceiving a message (block 322) at an associated inbox. In general, thestatus logic of a slave thread monitors the associated inbox to detectthe receipt of status requests (block 324). If a message is not a statusrequest (“N” branch of block 324), the slave thread processes themessage according to the software thread processing thereon (block 326).If the message is a status request (“Y” branch of block 324), the statuslogic of the slave thread determines a status associated with the slavethread (block 328), and the status logic communicates a status responsebased on the determined status to the master thread (block 330). Ingeneral, consistent with embodiments of the invention, the status logicmay automatically determine the status and communicate the statusresponse independent of the operation of the slave hardware thread. Forexample, a status response may be received at a slave hardware thread,and the status logic may determine the status and communicate the statusresponse concurrent with the slave hardware thread processing a softwarethread, i.e., processing of the software thread is not interrupted torespond to the status request. Thus, in many embodiments, the hardwarethread is never interrupted, and the associated software threadexecuting on that hardware thread is never notified of either thereceipt of a status request or the subsequent communication of a statusresponse.

Moreover, the status of the slave hardware thread may be based at leastin part on a software thread that the slave hardware thread isprocessing, including for example processing performance of the one ormore software threads being processed by the slave hardware thread.Hence, consistent with embodiments of the invention that distribute aworkload to one or more hardware threads, the master thread maydynamically retrieve/collect status information related to theprocessing of the workload, i.e., the status of each software threadexecuting on the associated slave hardware threads.

Consistent with some embodiments of the invention, the master thread andslave threads may utilize the DITC protocol to send messages (i.e.,status requests and responses). However, other messaging protocols(e.g., indirect inter-thread communications) and/or memory transactionsmay be used for communicating the status requests and responses. In someembodiments of the invention, messages may be broadcast to all slavethreads, or some subset of slave threads utilizing a thread mask. Amaster thread may send a broadcast a configuration message to configureall the slave threads for the desired status. This configuration may beencoded as a hardware managed performance counter configuration thatwould alleviate the need to involve software on the slave thread. Inaddition, the configuration message may interrupt the slave thread andinstruct the slave thread how to configure hardware of the slave thread(e.g., status logic and/or status register), and/or the configurationmessage may specify what status variables related to the hardware threadand/or the software thread processing thereon are desired to bereported/collected through the use of a status register and statuslogic.

Moreover, the master thread may initiate a status request that may besent to all slave threads, or a subset of slave threads. When the statusrequest is received it may be examined by the status logic of each slavethread. When possible, the status logic may automatically generate astatus response and send it to the master thread. A status response mayinclude data from a status register (e.g., a performance counter, adedicated special purpose register, and/or or any other state that maybe preconfigured as status information). In some embodiments, in thecase of complex status requests, processing of the software thread maybe interrupted so that the software layer may generate the statusresponse.

In some embodiments, the hardware of the master thread (e.g., the threadstatus logic) may receive all status responses and may perform severaldifferent actions. For example, the thread status logic of the masterthread may be configured to accumulate counts; ignore some responses;interrupt software for some responses; accumulate filtered responsesinto a locally accessible hardware buffer; or store responses out to amemory location. In addition, complex masks may be configured to controland filter what responses are stored. The hardware including the threadstatus logic may be configured with a status response time such that themaster thread may collect status responses for a predetermined periodbefore notifying software. Such configuration may be implemented tohandle the case where a slave thread is asleep and not responding. Insome embodiments, the thread status logic may simply require that allslave threads respond and use a simple counter to determine that allslave threads have responded. In addition, hardware resources may beconfigured with status logic consistent with embodiments of theinvention such that the status of such hardware resources may bedetermined as described herein. For example, a master thread may querythe status of connected non-processor hardware resources.

While the invention has been illustrated by a description of the variousembodiments and the examples, and while these embodiments have beendescribed in considerable detail, it is not the intention of theapplicants to restrict or in any other way limit the scope of theappended claims to such detail. For example, the blocks of any of theflowcharts may be re-ordered, processed serially and/or processedconcurrently without departing from the scope of the invention.Moreover, any of the flowcharts may include more or fewer blocks thanthose illustrated consistent with embodiments of the invention.

Additional advantages and modifications will readily appear to thoseskilled in the art. Thus, the invention in its broader aspects istherefore not limited to the specific details, representative apparatusand method, and illustrative example shown and described. In particular,any of the blocks of the above flowcharts may be deleted, augmented,made to be simultaneous with another, combined, or be otherwise alteredin accordance with the principles of the invention. Accordingly,departures may be made from such details without departing from thespirit or scope of applicants' general inventive concept.

What is claimed is:
 1. A method for retrieving a status for a slavehardware thread in a processing system comprising a plurality ofhardware threads configured in a plurality of interconnected integratedprocessor blocks, the method comprising: receiving a status request forthe slave hardware thread from a master hardware thread at an inbox; inresponse to receiving the status request at the inbox, determining astatus of the slave hardware thread using status logic associated withthe slave hardware thread, wherein the status logic is configured todetermine the status of the slave hardware thread without interruptingprocessing of the slave hardware thread; and communicating a statusresponse based on the status to the master hardware thread.
 2. Themethod of claim 1, wherein determining the status of the slave hardwarethread comprises analyzing a status register associated with the slavehardware thread with the status logic to determine the status.
 3. Themethod of claim 1, further comprising: receiving a configuration messageat the slave hardware thread from the master hardware thread; andprocessing the configuration message at the slave hardware thread toconfigure the status logic of the slave hardware thread to automaticallycommunicate a status response responsive to receiving a status requestto the master hardware thread.
 4. The method of claim 1, furthercomprising determining the status of the slave hardware thread andcommunicating the status response are performed concurrent withprocessing a software thread with the slave hardware thread.
 5. Themethod of claim 1, further comprising: receiving the status response atthe master hardware thread; and storing status information for the slavehardware thread to memory based at least in part on the received statusresponse.
 6. The method of claim 5, further comprising prior to storingthe status information for the slave hardware thread to memory,determining whether the status response is of a particular type byfiltering the status response with a mask using thread status logicassociated with the master hardware thread, wherein the statusinformation is stored to memory responsive to determining that thestatus response is of the particular type.
 7. The method of claim 1,further comprising: receiving the status response at the master hardwarethread; and determining whether the status response is of a particulartype.
 8. The method of claim 7, further comprising in response todetermining that the status response is of the particular type,communicating an interrupt message to the slave hardware thread.
 9. Themethod of claim 7, wherein determining whether the status response is ofa particular type comprises filtering the status response with threadstatus logic of the master hardware thread by with a mask.
 10. Themethod of claim 1, further comprising: communicating the status requestfrom the master hardware thread; monitoring the receipt of the statusresponse at the master hardware thread to determine whether the statusresponse was received within a predefined amount of time fromcommunicating the status request.
 11. The method of claim 10, furthercomprising communicating a notification from the master hardware threadresponsive to not receiving the status response within the predefinedamount of time.
 12. The method of claim 1, wherein the plurality ofhardware threads are connected to a network with a direct inter-threadcommunication interface.